Abstract: The object of this study is to observe the fluidization behaviour of liquid-solid and gas-liquid-solid fluidized beds with magnetic immobilized enzyme support particles as the solid phase in a uniform magnetic field. The voidage of the liquid-solid beds, the average gas holdup and the radial distribution of holdups of the gas-liquid-solid bed in magnetic fields were measured and correlated in empirical models. The fluidized bed in magnetic field was also used in an immobilized-cell catalized reaction system to test its applicability.